Rotunno C A, Vilallonga F A, Fernández M, Cereijido M
J Gen Physiol. 1970 Jun;55(6):716-35. doi: 10.1085/jgp.55.6.716.
The aim of this paper is twofold. First, to describe a method for the measurement of the unidirectional flux of Na from the outer bathing solution into epithelium (J(OT)), and second, to describe the use of this method under a variety of experimental conditions in order to obtain some insight into the nature of this flux. The method developed is based on the exposure of a frog skin to a Ringer solution containing (22)Na. The exposure is made so that neighboring points along the surface remain in contact with the (22)Na solution for gradually longer periods, ranging from 0 to 46 sec. Some 8 to 10 samples of the exposed part are used to obtain the time course of the uptake of (22)Na and this time course is used, in turn, to evaluate J(OT). This flux is then studied in skins mounted between two identical Ringer solutions with 115 mM Na (11.25 +/- 0.10 [18] micromole.hr(-2) cm(-2)), and in skins mounted with Ringer with 1 mM Na on the outside and 115 mM Na on the inside (0.43 +/- 0.05 [18] micromole.hr(-1).cm(-2). From the observations that the flux is much larger than the net Na flux across the whole skin, that it is inhibited by K(+), and is unaffected by ouabain, it is concluded that the penetration of Na(+) into the epithelium does not occur by simple diffusion and is not directly dependent on an ouabain-sensitive mechanism. In the course of these experiments it was observed that when the skin was crushed between two chambers the uptake of Na in the neighboring exposed areas was decreased.
本文的目的有两个。其一，描述一种测量钠从外部浴液进入上皮组织的单向通量（J(OT)）的方法；其二，描述在各种实验条件下使用该方法，以便对这种通量的性质有一些了解。所开发的方法基于将蛙皮暴露于含有(22)Na的林格氏液中。进行暴露时，使沿表面的相邻点与(22)Na溶液接触的时间逐渐延长，范围从0到46秒。使用约8至10个暴露部分的样本获取(22)Na摄取的时间进程，然后利用这个时间进程来评估J(OT)。接着在安装于两种相同的含115 mM钠的林格氏液之间的皮肤中研究这种通量（11.25 +/- 0.10 [18]微摩尔·小时(-2)·厘米(-2)），以及在外侧为1 mM钠而内侧为115 mM钠的林格氏液中安装的皮肤中研究这种通量（0.43 +/- 0.05 [18]微摩尔·小时(-1)·厘米(-2)）。从通量比整个皮肤的净钠通量大得多、它受到钾离子抑制且不受哇巴因影响的观察结果得出结论，钠离子进入上皮组织不是通过简单扩散发生的，也不直接依赖于对哇巴因敏感的机制。在这些实验过程中观察到，当皮肤在两个腔室之间被挤压时，相邻暴露区域的钠摄取量会减少。
